REGULATION OF STEROIDOGENESIS IN CRAYFISH MOLTING GLANDS - INVOLVEMENT OF PROTEIN-SYNTHESIS

The involvement of continuous protein synthesis in the mechanisms of c rustacean steroidogenesis was investigated using crayfish molting glan ds (Y-organs). During intermolt, Y-organ steroidogenic activity is low . Eyestalk ablation initiates premolt which is characterized by a rapi d increase in the production of ecdysteroids. In vitro incorporation o f [C-14]leucine into TCA-precipitable proteins was measured in Y-organ s. A significant increase of de novo protein synthesis was observed in the premolt stage compared to the intermolt stage. On the other hand, cycloheximide totally suppressed protein synthesis within 2 h and sim ultaneously led to a strong inhibition of the ecdysteroid synthesis. S inus gland extracts (containing molt inhibiting hormone) also induced both a limited but reproducible inhibition of Y-organ protein synthesi s and a pronounced inhibition of ecdysteroid production within 2 h. Th e results suggest a functional link between protein synthesis in the Y -organ and sustained ecdysteroid production. The analysis of autoradio graphs from one-dimensional gel electrophoreses revealed an overall in crease in de novo synthesis of glandular proteins in early premolt but also a more specific effect on distinct proteins (increase of 150, 14 0, 50-60, 22 and 15-18 kDa proteins) which may be more directly involv ed in the regulation of ecdysteroidogenesis.